NO. 2 ENCYCLOPEDIA OF INSECT ANATOMY — SNODGRASS Q 



(L, sutura, a seam) . This was probably first suggested by the sutures 

 in the vertebrate skull, which are formed by the coming together of 

 bones growing out from centers of ossification. The analogy has 

 given rise to the false impression that the insect skeleton with its 

 "sutures" is formed by the union of parts developing from separate 

 centers of sclerotization. 



Most of the grooves of the insect skeleton are actually lines of 

 cuticular inflection forming internal ridges to strengthen the body 

 wall in regions of mechanical stress. They are therefore not sutures 

 in any literal sense, and for descriptive purposes are better termed 

 sulci (L. sulcus, a groove or furrow). The Greek equivalent anlax 

 has also been used. 



In a few cases grooves of the insect skeleton are lines of secondary 

 union between sclerites. These might figuratively be called sutures. 



-Ite: A suffix used in biology to denote "a part of" some larger 

 unit, as in somite, podite, sclerite, etc. Very commonly it is appended 

 to tergiim and sternum giving tergite and sternite for the major plates 

 of the body segments. This usage, however, leaves us with no terms 

 for subdivisions of the plates which properly would be the tergites 

 and sternites. 



We encounter also the term gonocoxite applied to what is evidently 

 the coxa itself. The ite is here clearly unnecessary. The term coxo- 

 podite, however, is entirely correct since it means the coxal part of 

 a leg. 



Larva: The word is derived from Latin and means a spectre, a 

 ghost, a hobgoblin, or a mask. If we take the last meaning, a mask, a 

 young insect is best defined as a larva if it differs so much in ap- 

 pearance from its parents that it must be reared to determine its 

 identity. When a young insect resembles its parents except for the 

 full development of wings and reproductive capacity it is called a 

 nymph or, in some aquatic orders, a naiad. [This distinction between 

 and retention of the terms larva and nymph is not shared by many 

 entomologists. Most embryologists and physiologists today do not 

 make any distinction between the two ; any immature insect is called 

 a larva. — A. G. R.] 



Larvae of different species differ so much in the degree of de- 

 parture from the adult form that it is evident they have under- 

 gone various degrees of evolution diverging from the parental struc- 

 ture. Larvae therefore can in no sense be regarded as representing 

 ancestral adult forms of their species, nor can they be attributed to 

 "early hatching" of the embryo — once a popular theory. We must 



